Regulated deficit irrigation can decrease soil CO2 emissions in fruit orchards

Resumen

Irrigation water restrictions in the Mediterranean area have created a growing interest in water conservation. Apartfrom environmental and economic benefits by water savings, regulated deficit irrigation (RDI) may contributeto reduce soil CO2 emissions and enhance C sequestration in soils, by decreasing microbial and root activityin response to decreased soil moisture levels. An experiment was established in four orchards (peach, apricot,Saturn peach and grape) to investigate the effects of regulated deficit irrigation (RDI) on soil CO2 emissions.Two irrigation treatments were assayed: full irrigation (FI), and RDI, irrigated as FI except for postharvest period(peach, apricot, Saturn peach) or post-veraison period (grape) were 50% of FI was applied. The application ofdeficit caused a significant decrease in CO2 emission rates, with rates in average of 90 mg CO2-C m-2 h-1, 120 mgCO2-C m-2 h-1, 60 mg CO2-C m-2 h-1 and 60 mg CO2-C m-2 h-1 lower than FI during the period when deficitwas applied for peach, apricot, Saturn peach and grape. This confirms the high effectiveness of the RDI strategiesnot only to save water consumption but also to decrease soil CO2 emissions. However, monitoring during longerperiods is needed to verify that this trend is long-term maintained, and assess if soil carbon stocks are increase ormost CO2 emissions derive from root respiration.